Disposition of sulfonamides in food-producing animals. VII. Disposition of sulfathiazole in tissue, urine, and plasma of swine following intravenous administration.

Abstract

The tissue, urine, and plasma concentrations of sulfathiazole were determined at various times following intravenous administration to 15 swine. The average plasma and urine data were found to fit a two-compartment pharmacokinetic model-with a biological half-life of 2.6 hr and a total apparent volume of distribution of 0.625 liter/ kg body weight. The second compartment was found to be “shallow”;that is, the apparent volume of the second compartment was only 23% of the central compartment. Sulfathiazole was eliminated by excretion of unchanged drug into urine (48%) and formation of an acetyl metabolite (19%). Twelve of the swine appeared to be divided into six “rapid” and six “slow” acetylators. The data obtained from seven tissue sites paralleled the plasma concentration and confirmed that tissue residues of sulfathiazole can be calculated from plasma and/or urine concentrations of the drug.